Fuel storage tanks, such as the gasoline storage tanks service stations, which have been in place for many years occasionally develop small leaks which due to their size can remain undetected for long periods of time. In addition to the fire hazards involved, such leaks can allow the fuel to spread underground for considerable distances and result in contamination of water supplies, infiltration of the cellars of neighboring homes or damage to surrounding soil and plant life. Moreover, with the current awareness of environmental pollution, federal, state and local agencies are now imposing strict regulations and penalties for pollution from a variety of sources, including fuel storage tanks.
The Department of Environmental Protection has requested that a method known as the Petro-tite test be employed as the accepted "tightness" test to determine the integrity of underground fuel systems. The apparatus and method are described in U.S. Pat. No. 3,910,102 and its teachings are specifically incorporated herein by reference. In practice, this test consists of filling the system to a level and recording any loss of volume from that level over a period of time. Factors, such as the recorded volume change, temperature change and tank end deflection are used to calculate any actual volume loss. This test is a very reliable one except when air pockets are present in the system, particularly in an underground storage tank. Since the measurement assumes a one hundred percent liquid filled system, the presence of an air pocket distorts the actual reading. Any air trapped in the tank acts as a spring under force and behaves differently to temperature changes than do liquids. The effect of the trapped air on the volume change necessitates removal before an accurate measurement can be made. The method usually employed for the removal of trapped air is to excavate down to the top of the tank and open a fitting to allow the air to escape. The tank is then closed and the test continued. This method is both expensive and time consuming. Accordingly, the instant invention provides an apparatus and method heretofore unknown in the industry, which removes these air pockets without costly and time consuming excavation of the buried storage tank.
It is therefore an object of this invention to provide a process and device for the removal of air pockets in underground storage tanks. Another object is to provide a process and device which can accurately locate and remove air pockets in underground storage tanks so that an accurate measurement can be made as to whether such tank is leaking. A further object of the present invention is to provide a process and device which can be employed to remove air pockets in underground fuel storage tanks without the need for excavating to the fuel tank itself. Another object of this invention is to provide a process and device which is simple and can be operated without excavation or major interruption of existing fuel dispensing facilities. These and other objects will readily become apparent to those skilled in the art in the light of the teachings herein set forth